The present invention relates generally to computer systems and more specifically to window systems for computer system displays.
In order to improve the interface with an operator, many current computer systems use window systems for their display output. In a window system, several windows are used to receive computer output from different concurrently running processes, or different portions of output from a single process. A window can be thought of as a logical output device to which the computer can write.
On a cathode ray tube (CRT) display screen, a window is typically a rectangular region. The size, shape and location of the window may be changed by the user. In addition, windows may overlap each other, with underlying windows being partially or completely covered. This is often referred to as the desktop metaphor, in which each window resembles a piece of paper laying on a desk top. In the same way in which pieces of paper may be moved about on the desk top, and restacked so that different pieces of paper are exposed, the windows can be moved about on the display screen.
Even though a window may be partially or entirely covered, the computer will continue to write information to that window. Sometimes it is desirable for an operator to be able to observe a part of a particular window which is otherwise covered. This may be useful, for example, in determining the progress of processes running concurrently with one to which the operator's main attention is directed. However, it is not often easy, and sometimes not even possible to expose necessary portions of windows which are otherwise covered. It would be desirable to provide a mechanism whereby selected portions of covered windows can be displayed without significantly rearranging the windows in the display.
It is therefore an object of the present invention to provide a window system which allows partially or completely covered windows to be inspected while they otherwise remain covered.
Therefore, according to the present invention, a porthole window is generated in the window system. This porthole window provides an opening within upper layer windows which looks through into a covered window or a covered portion of a partially exposed window. This porthole window reflects any changes which are made to the covered window.
The novel features which characterize the present invention are defined by the appended claims. The foregoing and other objects and advantages of the present invention will hereafter appear, and for purposes of illustration, but not of limitation, three preferred embodiments are shown in the accompanying drawings.